Surface Roughness Properties Research Articles

Bio-exfoliated Boron nanosheet as an effective contact lens care solution against ocular bacterial infections

The utility of contact lenses is increasing globally, with their use extending to therapeutic, cosmetic, and drug delivery purposes for ocular infections. However, due to improper hygiene, poor handling techniques, and extended wear, about 63% of contact lens wearers worldwide have been affected by ocular microbial infections. This has led to increased microbial resistance to ocular drugs, prompting the development of nano-based contact lens care solutions. 2D boron nanosheets have gained significant attention due to their structural similarity to graphene. The present study focuses on synthesizing boron nanosheets from the precursor MgB2 by bio-exfoliation of MgB2, utilizing plant parts of Pisonia grandis, Plantago ovata, Annona reticulata, Cyanodon dactylon, where the Mg atoms are selectively chelated and boron layers are exfoliated to form boron nanosheets. The synthesized boron nanosheets are characterized and analyzed for its anti-bacterial activity against Bacillus cereus, Escherichia coli, Staphylococcus aureus, Klebsiella pneumonia of which boron nanosheet possess selective zone of inhibition against B. cereus. The toxicity of boron nanosheets has been analyzed using Artemia salina, where boron nanosheets are less toxic. Boron nanosheets with good antibacterial properties and less toxicity have been further analyzed for their potential use as contact lens care solutions where various parameters, including Light transmittance, Wettability, Surface roughness, Antibacterial activity, and other physicochemical properties were analyzed. The results indicate that boron nanosheets could be effectively used as contact lens care solutions for bacterial infections. This study serves as a platform for further exploration of 2D boron nanosheets in ocular drug delivery systems.

Effect of post-processing on the surface, optical, mechanical, and dimensional properties of 3D-printed orthodontic clear retainers

ObjectivesTo address the high surface roughness and poor optical properties of three-dimensional (3D) printed orthodontic clear retainers, an alternative post-processing protocol was investigated with the goal of achieving improved surface, optical, and mechanical properties while preserving dimensional accuracy.Materials and methodsSamples were prepared from two biocompatible methacrylate-based 3D-printing resins (Formlabs Dental LT Clear V2, NextDent OrthoFlex) and one thermoplastic material (Duran). For the 3D-printed resins, one group was post-processed by rinsing in isopropyl alcohol, while another group was centrifuged before post-curing in glycerine. Three different testing conditions were used: dry, wet (24-h water immersion), and aged (thermocycling for 10,000 cycles). Surface characteristics were evaluated qualitatively and quantitatively. Optical properties were assessed for transparency and colour stability, while mechanical properties were elicited from tensile and microhardness tests. Water sorption and solubility were calculated. Samples mounted on a dental model were scanned by micro-computed tomography to measure thickness and gap width.Results3D-printed samples post-processed by centrifugation showed significantly decreased surface roughness and improved visible light transmission, colour stability, tensile strength, and hardness. The centrifuged samples showed significantly increased thickness, while designing an offset equal to this thickness improved the adaptation.ConclusionsPost-processing by centrifugation produces surface coating that enhances the surface and optical properties of the 3D-printed orthodontic retainers, while curing in an oxygen-free environment improves their mechanical properties. Design modifications may be necessary for this protocol to ensure proper adaptation to the dentition.Clinical relevanceProper design and post-processing protocols are necessary to achieve the desired properties of orthodontic clear retainers.

Comparison of physical, mechanical, and optical properties between thermoplastic materials and 3-dimensional printing resins for orthodontic clear retainers.

This study investigated the physical, mechanical, and optical properties of 3-dimensional (3D) printing resins compared with thermoplastic materials to evaluate their suitability for the fabrication of orthodontic clear retainers. Samples were prepared from thermoplastic sheets (Duran [Scheu-Dental GmbH, Iserlohn, Germany] and Zendura [Bay Materials LLC, Fremont, Calif]) and biocompatible 3D-printing resins (Dental LT Clear V2 [Formlabs Inc, Somerville, Mass] and OrthoFlex [Nextdent BV, Soesterberg, The Netherlands]) according to the manufacturer's instructions. The materials were characterized by Fourier transform infrared spectroscopy, differential scanning calorimetry, and water sorption tests. Mechanical properties were assessed by tensile tests and hardness under 3 different conditions: dry, wet (24-hour water immersion), and aged (thermocyled for 10,000 cycles). Surface characteristics were qualitatively and quantitatively evaluated by scanning electron microscopy and 3D confocal imaging, respectively. Optical properties were assessed by ultraviolet-visible spectroscopy and color stability tests by immersion into various staining solutions. The mechanical properties of the 3D-printing resins were more markedly altered in different testing conditions (dry, wet, and aged) than in thermoplastic materials. The surface roughness, transparency, and color stability of 3D-printing resins are significantly inferior, especially NextDent OrthoFlex. The evaluated 3D-printing resins are more brittle and less ductile compared with the thermoplastic materials. The 3D-printing resins also do not meet the clinical thresholds of surface roughness and optical properties for the fabrication of orthodontic clear retainers. Further postprocessing of the 3D-printing resins may be required to improve these properties.

Detailed Analysis of Friction in Water-Lubricated Bearings Under Boundary Lubrication: Model Development and Experimental Validation

Abstract A novel friction model for water-lubricated bearings under boundary lubrication conditions is proposed. The effects of speed, load, surface roughness, and material properties on the friction coefficient are examined. The model is validated through experimental tests using NBR and UHMWPE materials, demonstrating reliability and applicability. The impact of varying speed and load on lubrication states is analyzed, with a focus on the behavior of microconvex contact friction under boundary lubrication conditions. Based on the verified friction model, the influence of surface roughness and texture direction on bearing performance is also explored, offering actionable insights for optimizing bearing design. This model provides critical insights for enhancing friction management and noise reduction in water-lubricated bearings, offering valuable guidance for their design and manufacturing.

Optimizing shot peening process parameters on surface roughness, hardness, and wear properties of ti6al4v peened with stainless steel shots

Optimizing shot peening process parameters on surface roughness, hardness, and wear properties of ti6al4v peened with stainless steel shots

An experimental investigation on AA5083 alloy shot peening surface characteristics

The research examines how varying shot peening parameters affect the surface properties of AA5083 aluminum alloy, specifically looking at topography, mechanical traits, and surface morphology. Shot peening treatment is conducted using a custom system with stainless steel shots ranging from 4–8 mm diameter, peening durations of 30–60 min, and shaft speeds of 500–1000 rpm. Surface characteristics are assessed through hardness depth-wise measurement, surface roughness, and tensile properties. The study investigates phase transformation and grain refinements using X-Ray Diffraction (XRD), Electron Backscatter Diffraction (EBSD), and Transmission Electron Microscope (TEM). Full-depth profile and lattice strain study with localized plastic strain are analyzed using XRD, with EBSD estimating the depth of plastically strained regions. A multi-criteria decision-making approach is used to identify the optimal peening parameters based on hardness, tensile strength, and surface roughness, employing analysis of variance (ANOVA) and Grey Regression analysis.

Significance of the electrochemical passive layer during the wear tests of surface finished SLM stainless steel features

Tribology, the study of friction, wear, and lubrication, plays a critical role in the performance of manufactured components, particularly in the emerging field of additive manufacturing (AM). While AM allows for the fabrication of complex geometries, the as-built components often suffer from surface roughness and suboptimal mechanical properties, necessitating post-processing treatments to enhance their usability. In this paper, a specific heat treatment sequence, including main quenching, intermediate quenching, and tempering, was applied to stainless steel 316L samples to improve their mechanical characteristics. The main quenching involved heating the samples to 1000°C for 30minutes, followed by water quenching. The intermediate quenching followed a similar process at 750°C. The heat-treated samples (HT-1 and HT-2) underwent different tempering stages. The HT-1 samples were selected for tribological testing due to their lower residual stresses and higher hardness compared to HT-2 samples, with both samples demonstrating similar ductility. HT-1 samples were tested against six different hard counter body materials under varying surface roughness conditions achieved through electrochemical polishing. The electrochemically fully finished (ECP) samples achieving the lowest coefficient of friction (COF) compared to as-built samples. Wear mechanisms varied with the counter body materials: adhesive wear and tribo-oxidation were dominant against hardened steel, alumina (Al2O3), boron carbide (B4C), and silicon carbide (SiC), while abrasive wear was predominant against tungsten carbide (WC) and titanium carbide (TiC).

Dual-laser powder bed fusion using 450 nm diode area melting and 1064 nm galvo-scanning fiber laser sources

This study introduces an innovative dual laser powder bed fusion (PBF-LB/D) system, which combines two distinct laser processing methods to enhance control over microstructural outcomes. Unlike conventional PBF-LB systems that employ a single laser type, this dual-laser setup integrates a traversing Diode Area Melting (DAM) laser head with multiple 450 nm diode lasers (4 W each) and a traditional high-power (200 W) 1064 nm fiber-laser. This unique configuration allows for significantly different melt pool solidification rates within the same layer. For the first time, Ti6Al4V feedstock was processed using both laser types within a single sample. A specific scanning strategy defined separate laser processing regions, including an overlap where both lasers interacted to fuse the feedstock and bridge the two regions. The fiber-laser melted (FLM) regions experienced much higher cooling rates (∼107 °C/s) than the DAM regions (∼600 °C/s), resulting in acicular ά/α phases. In contrast, DAM regions exhibited larger grains, with parent β grain sizes approximately 13 times larger than those in the FLM zone. This dual laser system investigation not only demonstrates microstructural in-situ spatial tailoring but also highlights variations in the laser-induced heat-affected zone, surface roughness, and mechanical properties across different regions within the fabricated Ti6Al4V samples.

Enhancing anti-icing efficacy in hybrid polyurethane coatings: Evaluating the significance of molecular weight, chemical structure, and content of PEG/PDMS

This study investigates the advantages of adding polydimethyl siloxane/polyethylene glycol (PEG/PDMS) copolymers to polyurethane coatings, with a particular focus on optimizing anti-icing efficacy. A range of characterization techniques are applied, including attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy, X-ray photoelectron spectroscopy (XPS) analysis, surface roughness measurements, wettability analysis, tensile testing, and ice adhesion measurements, to elucidate the intricate relationships between copolymer molecular weight, chemical structure, and content and their collective effect on the anti-icing properties of the developed coatings. Tailored PEG/PDMS copolymers significantly reduce ice nucleation temperatures and enhance the anti-icing properties of polyurethane coatings. Adding PEG/PDMS copolymers to polyurethane alters the surface roughness, wettability, and mechanical properties of the coatings to improve anti-icing performance. The presence of copolymers decreases ice adhesion strength (<50 kPa), attributed to the formation of a quasi-liquid layer that acts as a lubricant between the ice and the coatings, and delays ice formation. Furthermore, the enhanced durability of copolymer-containing coatings ensures a long-lasting anti-icing effect after multiple icing/de-icing cycles, although some degradation was observed over time. The tailored PEG/PDMS copolymers demonstrate potential for maximizing the anti-icing properties of polyurethane coatings and advancing anti-icing technologies.

Physical and Mechanical Properties of Bulk-fill Resin Composites Submitted to Additional Polymerization for Use in Semi-direct Restorations.

Physical and mechanical properties of high-viscosity bulk-fill resin composites submitted to additional polymerization for semi-direct use were evaluated. Filtek Z350 XT, Aura Bulk Fill, Beautifil Bulk Restorative, Filtek One Bulk Fill Restorative, and Tetric N-Ceram Bulk Fill were submitted to additional polymerization to evaluate sorption, solubility, surface microhardness, surface roughness before and after simulated brushing, color stability after coffee staining, flexural strength, elastic modulus, and modulus of resilience. Filtek Z350 XT and Filtek One Bulk Fill Restorative showed higher sorption values, while Aura Bulk Fill showed higher solubility (p<0.0001). Microhardness values were significantly higher for Filtek Z350 XT (p<0.0001). Roughness increased after wear for all resins (p<0.05). All resins exhibited staining, with significantly higher ΔEab, ΔE00, and ΔWID values observed for Beautifil Bulk Restorative (p<0.0001). Flexural strength values were higher for Filtek Z350 XT and Filtek One Bulk Fill Restorative in comparison with the others (p<0.0001). Filtek One Bulk-Fill had higher elastic modulus and modulus of resilience values (p<0.0001). Physical and mechanical properties varied according to the composition. None of the bulk-fill resins showed surface microhardness and roughness properties after brushing similar to or superior to those of the conventional type. Color stability after staining depended on resin composition, with Beautifil Bulk Restorative showing more intense staining.

Study on the Abrasive Blasting Mechanism of Solder Welded 304V Wire in Vascular Intervention.

The solder burrs on the 304V wire surface can easily scratch the vascular tissue during interventional treatment, resulting in complications such as medial tears, bleeding, dissection, and rupture. Abrasive blasting is often used to remove solder burr and obtain a smooth surface for the interventional device. This study conducted an abrasive blasting experiment to explore the effects of process parameters (air pressure, lift-off height, abrasive volume, and abrasive type) on processing time, surface roughness, and mechanical properties to reveal the material removal mechanism. The results indicated that the resin abrasive can remove the SAC burr and keep the 304V integrity due to the proper hardness and Young's module. Impaction pits are the main material removal mode in abrasive blasting. The processing time decreases with the increase in air pressure. The surface roughness increases with the increase in abrasive volume. The primary and secondary factors affecting the surface roughness of the 304V wire after abrasive blasting are the abrasive type and air pressure, followed by the abrasive volume and lift-off height. Blasting leads to a decrease in yield strength, and Young's modulus and the hardness of the abrasive will affect the tensile strength. This study lays a foundation for understanding abrasive blasting and different cutting mechanisms.

Influence of material orientation, loading angle, and single-shot repetition of laser shock peening on surface roughness properties

Titanium alloy Ti6Al4V is extensively utilized in biomedical applications due to its excellent biocompatibility, corrosion resistance, and mechanical properties. The design of dental implant surface textures has changed throughout time to address issues with oral rehabilitation in both healthy and damaged bones. The longevity of an implant is significantly impacted by surface roughness. This study examines the use of laser shock peening (LSP) as a surface modification technique to improve the mechanical properties of implants. A numerical model is developed using the commercial finite elements software in ABAQUS/Explicit for simulating dynamic conditions. The aim of the study is to develop surface roughness parameters using computational methods such as studies have not yet been contemplated. The single shot angle, shot repeat, time, material orientation, and laser power are applied for the first time simultaneously to evaluate the impact of material orientation and loading angles on surface roughness parameters. The study showed that the developed computational model’s compressive residual stress was −578.45 MPa, while the experimental samples were −592.18 MPa. Consequently, the difference between the computational and experimental results was 2.32%. Without regard to material orientation or angle, the compressive residual stress of the samples under examination was found to be −578.450 MPa after three repetitions and to decreased to −1.620 MPa after four. These results demonstrate that by varying the material orientation and loading angle, the Ra value may be increased four times.

Surface integrity and mechanical properties of small elements fabricated through LPBF and post-processed with heat treatment and abrasive machining

The present research analyzes the impact of heat treatment atmosphere followed by finishing surface machining of small elements of Inconel 939 fabricated through laser powder bed fusion (LPBF). The analysis involved annealing in two gas mediums, solution treatment, and aging to achieve the desired microstructure and mechanical properties. The finishing surface was performed using various variants of abrasive machining. A more than fivefold reduction in the average roughness height Ra from 5.6 µm to 1.15 µm was achieved using metal balls as an abrasive, which was required for further processing. Residual stress tests have shown that due to heat and abrasive treatment, tensile stresses change into compressive ones. After printing, samples are characterized by tensile residual stresses on the surface (+ 428 MPa), while after heat treatment, compressive stresses occur (− 179 MPa). Abrasive machining with metal balls increases the value of compressive stresses to − 464 MPa. In addition, the impact of post-processing on the microstructure of Inconel 939 was discussed in terms of mechanical properties. The yield strength of 1184 MPa and elongation values of 19.3% were obtained for samples after HT in an argon atmosphere and abrasive machining with a ceramics roller. These studies provide valuable new information on the effective heat treatment and optimization of the finishing machining of Inconel 939, especially in achieving the desired surface roughness, microstructure, and mechanical properties for aerospace applications.

Effects of argon plasma treatment on carbon fiber surface characteric and its reinforcing polyimide composites interfacial properties at room and elevated temperatures

In high temperature conditions, this can cause considerable changes in the mechanical properties of the composite. In order to determine the structural and mechanical property changes that occur in composite materials at elevated temperatures, to elucidate the damage mechanisms at elevated temperatures, and to improve the stability and durability of the materials. This paper studies how plasma treatment time affects the surface polarity, roughness, wettability and mechanical properties of carbon fibers. The results showed that the best wettability was attained after 10 min of plasma treatment, and new oxygen-containing functional groups (COO- and -C=O) developed on the fiber surface. The fundamental explanation is that during plasma surface treatment, the CH group in the bisphenol A part chain segment present in the epoxy resin sizing agent's composition is oxidized, forming an organic oxide layer. In this paper, the plasma modification technology was utilized to improve the interfacial compatibility of carbon fiber and Polyimide (PI) resin, and the interlaminar shear strength reached 103.98 MPa, up 10.49 %, and the strength retention rate was 84.3 % at 300 °C. In this paper, the plasma modification technique was employed to increase the interfacial compatibility of carbon fiber and PI resin. It was found that the Inductively Coupled Plasma (ICP) treated carbon fiber surfaces underwent physical and chemical changes that effectively enhanced the interfacial compatibility with the resin. However, the chemical groups and physically etched regions on the surface of the plasma-modified fibers are able to impede the relative motion of the resin to a certain extent, thus improving the interfacial strength.

Investigating novel thin-film nanocomposite membranes for sustainable water recovery using fertilizer-driven forward osmosis – Experimental and machine learning approaches

Water recovery from municipal wastewater can augment freshwater resources to meet increasing demand. An osmotic-driven membrane separation process- forward osmosis (FO) is currently being explored as a sustainable technology. This work proposes to address the challenges associated with FO namely (i) robust membrane and (ii) draw solute (DS) recovery. Robust thin-film nanocomposite membranes incorporating a) nickel ferrite or b) nitrogen-enriched nanoporous polytriazine (NENP-1) covalent organic framework were fabricated with enhanced hydrophilicity, surface roughness and anti-fouling properties. The optimum membranes M2 and C2 displayed a pure water flux of 4.86 ± 0.11 and 5.4 ± 0.2 L/m2h respectively and a specific reverse solute flux (SRSF) <<1 when using 1 M NaCl solution as the DS (feed solution – DI water). Fertilizer-driven FO (FDFO) was proposed as the diluted DS need not be recovered but could be used directly for irrigation. The pure water flux for both M2 and C2 membranes were in the following order for the fertilizers used as DS (1 M) - (NH4)2SO4 + (NH₄)₂HPO₄ > (NH4)2SO4 > (NH₄)₂HPO₄ which indicates that the mixed ions in the DS enhanced the water permeance. In all cases, the SRSF was < 1 g/L indicating the feasibility of the process. The membranes exhibited a TOC removal of > 90 % from synthetic municipal wastewater containing persistent organic pollutants and personal & pharmaceutical care products and the membranes could be regenerated after washing with a 10 mM solution of SDS for 5 cycles of operation. Further, ANN was used to develop a predictive model for water flux in FO membranes and the optimized architecture of 7–5–50–40–1 displayed a remarkable overall R2 value of 0.98 (MSE= 0.027). The FDFO process using the fabricated thin-film nanocomposite membranes holds enormous potential to be investigated in larger-scale studies.

Surface engineering for enhanced wicking: The role of laser machining and surface roughness

Wicking is an efficient liquid-handling strategy used in biomedicine, textile engineering, and environmental monitoring. Laser micromachining is a powerful method that induces unidirectional wicking by altering a surface's physical and chemical properties in one step. This research examines how laser machining affects the wicking dynamics of open microchannels. Microchannels were fabricated on a pre-laser-machined hydrophobic square on a silicon substrate, and their wicking performance, i.e., flow rate, water meniscus shape, and durability, was evaluated under various conditions, including different laser parameters, channel orientation, and engraving designs. Depending on its distribution, surface roughness, influenced by laser parameters, is critical in enhancing or hindering wicking. The laser can create two distinct wicking modes on a single platform. Increased roughness slows wicking in horizontally oriented channels, while in vertically oriented channels, it significantly boosts the capillary rate. The durability of wicking also depends on surface roughness properties; microchannels with tightly structured textures maintain durable wicking independent of their capillary flow rate. This study provides insights into how laser machining influences wicking dynamics in microstructures, offering strategies for optimizing microfluidic devices.

Bioinspired skin-like in vitro model for investigating catheter-related bloodstream infections

Intravenous (IV) catheter-related bloodstream infections (CRBSIs) cause significant risks in healthcare, necessitating advancements in catheter design and materials. This study investigates the effectiveness of Ecoflex, a silicone-based material, in studying CRBSIs through the development of skin-like replicas that mimic human skin properties for use in wearable sensing devices. We characterized the replica’s bioinspired surface roughness, wettability, bacterial adhesion, and mechanical properties and validated its performance using in vitro IV simulation. The results demonstrated that the bioinspired model replicates human skin textures with less than 7.5% error for surface roughness ranging from 0.05 μm to 6.3 μm. Wettability tests revealed that the artificial sebum application significantly reduced the static contact angles for deionized water and artificial sweat. Comprehensive mechanical testing revealed material high elasticity and resilience, suitable for dynamic biomedical applications. Bacterial adhesion studies using Staphylococcus epidermidis showed varying adhesion patterns influenced by surface roughness, highlighting the potential for material texture to impact infection risk. In IV therapy simulations, we observed bacterial growth dynamics over the incubation period. Our findings suggest that Ecoflex-based skin-like replicas can serve as a valuable tool for developing and testing new catheters, while the potential for use in other medical innovation devices, including wearable sensing devices, ultimately contributes to improved patient outcomes and infection control strategies.

Mechanical, Adhesive and Surface Properties of a Zirconia-Reinforced Lithium Silicate CAD/CAM Ceramic Exposed to Different Etching Protocols.

The aim of this investigation was to evaluate the effect of etching protocols on bond strength, surface roughness, and mechanical properties of a zirconia-reinforced lithium silicate (ZLS) CAD/CAM-ceramic. In total, 100 bars (ISO 6872), 75 plaques, and 25 cubes were cut from ZLS blocks(Vita Suprinity®). The surfaces were standardized, crystallized and divided into five groups: 1. control (no/treatment-C), 2. 5%-Hydrofluoric-acid (HF)/20 s (HF5%20s), 3.HF5%60s, 4.HF10%20s, and 5.HF10%60s. Flexural strength (FS) (three-point bending test, 1 mm/min), roughness (Pa), and micro-shear bond-strength (µSBS) tests were performed. The data were statistically analyzed with one-way ANOVA, Tukey's test (p ˂ 0.05) and Weibull (FS data). C showed higher Pa (1.176 ± 0.370 µm) than HF10%60s (0.627 ± 0.236 µm) and all other groups. Groups C and 20 s showed the most irregular surface patterns. The FS results were not influenced by etching protocols, while the Weibull modulus was, with the 5%HF groups being the most reliable (m: 5.63/6.70), while C and HF10%60s (m: 2.78/2.73) were the least reliable. All fractures originated from surface defects on the treated side of specimens. The 5%HF groups showed higher µSBS (20 s: 21.35 ± 4.70 MPa; 60 s: 23.50 ± 4.27 MPa) than the 10%HF groups (20 s: 14.51 ± 2.47 MPa; 60 s: 16.54 ± 3.12 MPa) and C (6.46 ± 2.71 MPa). The most prevalent failure pattern was "mixed" for etched groups, and "adhesive" for C. Etching protocols affect the evaluated properties by roughening materials' surface and, in some cases, regularizing surface defects. The best overall outcomes were achieved when applying 5%HF.

Effects of atmospheric pressure plasma treatment and its aging behaviors on interfacial strength of PI/PEEK composite film

AbstractSince the properties of surface roughness with time and the wettability pattern of polymer surfaces transformed by plasma remain unclear. In order to understand the mechanism of aging effect on film properties, this paper analyzes the aging of plasma‐treated PI films. The optimal treatment conditions were first explored by adjusting the plasma treatment power. Based on the effect of plasma treatment power on the surface physicochemical properties and mechanical properties of PI films. It was found that the content of oxygen‐containing functional groups on the surface of the film was highest at a plasma treatment power of 800 W, and the surface energy reached a maximum value of 67.71 mJ/m2. As the treatment power increases, the surface etching of the PI film increases significantly, as does the roughness. However, if the power is too high, it can cause excessive etching, resulting in peeling of the film surface. In addition, the mechanical properties of the films decreased with increasing plasma treatment power. Based on the effect of plasma treatment power on the surface physicochemical and mechanical properties of PI films, the best overall modification effect of PI films was determined when the treatment power was 800 W and the speed was 6 mm/s. And at 800 W, the peel strength of the PI/PEEK composite film reached a maximum value of 9.55 N/cm, which was 77.84% higher than that of the untreated composite film. However, plasma‐treated PI films can experience surface remodeling after being exposed to air for a period of time. In this paper, the wettability as well as the mechanical properties of the films are analyzed for different aging times. The results showed that after 30 days of plasma treatment, the O/C and N/C contents on the surface of the PI film decreased, and the wettability performance decreased by 19.45% compared with that of the recently treated film.

An In-Depth Exploration of Numerical Simulations for Stress Fields in Multi-Directional Rolling Processes

To address issues such as large surface roughness, coarse grains, and poor mechanical properties in low-carbon steel parts produced through wire arc additive manufacturing (WAAM), this paper proposes a method combining multi-directional incremental forming with the WAAM process. The additive manufacturing and cooling processes were simulated using the finite element software Abaqus to analyze the effects of multi-directional additive manufacturing on the stress field of the fabricated parts. The results indicate that after multi-directional incremental forming, the residual stress in the fabricated parts shifts from tensile stress to compressive stress, thereby reducing the risk of defects such as cracks. Moreover, the equivalent plastic strain of the processed parts increases, and the surface microhardness improves, with the most significant impact of multi-directional incremental forming observed in the contact area of the rolling head.